This invention relates to fibre-optic cable assemblies, their methods of manufacture, and pyrometers.
The invention is more particularly, but not exclusively, concerned with assemblies for use in radiation pyrometry.
In radiation pyrometry, and other applications in a high-temperature environment, it can be desirable to mount a radiation detector remotely from the source or object being monitored and to use a fibre-optic cable to transmit radiation to the detector. This can also have advantages in normal environments where access is restricted, since the fibre-optic cable can readily be mounted in inaccessible locations and where space is limited.
Conventionally, a lens or other device is used to focus radiation from a source onto the end of the cable. Where it is necessary to distinguish between radiation from different parts of the source, a coherent bundle of fibres may be used. In this way, since each fibre in the bundle has both ends at identical locations, an image focussed on one end of the cable is reproduced identically at the other end. Coherent fibre bundles are, however, difficult to manufacture and are considerably more expensive than non-coherent bundles. Alternatively, the fibre-optic cable may have several separate non-coherent bundles of fibres, the ends of which are spaced apart from one another in a row at one end of the cable, and the other ends of which can be led off to separate detectors. While this arrangement is less expensive, it suffers from the disadvantage of being less efficient because only a small proportion of the radiation captured by the lens is transmitted along the cable.